#include<stdio.h>
int main()
{
    int weight[3];
    char name[3] = {'A','B','C'}, result;
    for(int i = 0; i < 3; i ++) {
        scanf("%d",&weight[i]);
    }
    if (weight[0] == weight[1]) {
        result = name[2];
    }
    else if (weight[0] == weight[2]) {
        result = name[1];
    }
    else if (weight[1] == weight[2]) {
        result = name[0];
    }
    printf("%c",result);
    return 0;
}